178 OBSERVATIONS ON NEBULA 



angle, where lies Herschel's resolvable knot. And, if I mistake not, all the space from this 

 star to the vertex of the bend is filled up with extremely faint light. The knot is isolated 

 from the rest of the nebula, and the vacancy in which it is situated is closed in on the right 



and left hand, but, I think, not above and below, or, at least, above The nebula 



at the external angle stretches much farther towards the north preceding than in Herschel's 

 figure, but with a faint shade. Mr. Smith confirms my view of his ray. 



Aug. 14. — Finished the delineation of the nebula 17 of Messier by the mode of lines. 

 The larger knot stretches faintly upwards to a second nucleus, or rather star, just above. 

 With close attention, I am almost satisfied it is a very small star. The curve of the bright 

 following branch is much as in Herschel's drawing; I think the curve of the faint bend dif- 

 fers more materially. 



Aug. 19. — Attempted some observation on Messier 17, but the moon interferes. It is too 

 late for the star seen on the 14th, in Herschel's knot, to be verified by Mr. Smith. Farther 

 re-examination was desirable upon this nebula, and the places of the stars it contained, but 

 such is now impracticable. 



19. Nelmla h. 2092 and 2093. 



1839. July. — (There were several observations of little importance during the month of 

 July, in which these two nebulae were noted as separate, and the peculiarities of Herschel's 

 description recorded as being " well seen.") 



Aug. 1. — The faint band suspected between V. 14 and 2093 of Herschel's catalogue is 

 fully confirmed by this evening's observation. Mr. Smith and myself were both able to 

 trace the nebula continuously from one to the other, and the reverse, so that these are now 

 satisfactorily ascertained to constitute one immense nebula, stretching through several fields 

 of 30' diameter. From the right ascensions and declinations of these two nebulae, as given 

 by Herschel, the whole cannot well be less than 2° or 3° long. The double star mentioned 

 by Herschel is seen, as also the trapezium near the bifurcation, but the latter is evidently 

 somewhat distorted in his figure. The peculiar characteristic of the upper portion of the 

 nebula cannot be mistaken. I can think of no comparison as good as that which Herschel 

 gives it, that of a network, or interlacing of nebula. The stars follow the disposition of this 

 network very perfectly, and their real connexion with the nebula is as obvious as the testi- 

 mony of the eye and of common sense can make it. It is almost impossible that the pheno- 

 menon can result from a mere superposition of stars; indeed, the chances against the suppo- 

 sition of their independence of each other must be very nearly infinite. 



Aug. 3. — Attempted a triangulation among the principal stars in the great Nebula Cygni, 

 to assist in exactly copying the nebula. Thirteen were thus taken, their angles of position 

 with each other, and comparative distances carefully estimated and called out by one of us, 

 while the other recorded. The power used was the ordinary observing pov/er of 80. 



